claw

You never know what you’ll find when you open the projects feed on Hackaday.io. Most weeks, The Hacklet follows a theme of some sort. Sometimes I find projects that just look so cool that I have to get the word out about them.

Such is the case with this week’s first project, Mr. Runner created by [Alex Martin]. Mr. Runner is a quadruped robot that really looks the part. In fact, I’d say it looks like it’s ready to jump off the bench top. Like many of us, [Alex] has been inspired by Boston Dynamics, specifically their Wildcat robot. Wildcat had [Alex] searching the net for walking robot designs. He struck up something he liked with the work of [Dr. Fumiya Iida] and [Dr. Rolf Pfiefer]. In the mid 2000’s, the pair worked out of the University of Zurich. Mr. Runner is based upon their work, with plenty of design tweaks from [Alex].

The basic design is a quadruped with two servos per leg. The servos are at the body and the upper half of the leg. The knee and lower leg are connected by levers and a spring, forming something of a 4 bar linkage. The spring acts as a tendon, absorbing shock, and allowing energy from the servo to be stored and released while the robot runs. [Alex] is experimenting with gaits, controlled by a PC.

Mr. Runner wouldn’t be doing much running without a way to control those 8 servos. [Alex] started with an Arduino and a LynxMotion serial servo controller. This pairing served him well for the first generation of Mr. Runner. For the new version of the robot, he’s rolling his own board based upon Lynxmotion’sBotBoarduino. The Gerber files have been sent off to OSH Park, and in about a week, Mr. Runner will be off to the races.

Another great recently updated project is Arcade Claw Game Claw Build by [Alex Anderson]. I spent way too many hours of my youth in arcades, and more than a few quarters went into claw games. Sure, they’re usually rigged, but who hasn’t been pulled in by the chance to test your skill and win a prize? A friend asked [Alex] to design an arcade style claw for a game. A seasoned CNC and 3D printing master, [Alex] grabbed his notebook and started sketching. Rack and pinion designs would work well, but didn’t within the constraints of the game. A leadscrew based design would also work, but would be two expensive. Finally, [Alex] settled on a design and fired up his CAD software. He started with two jaw systems to prove out the basic system. Once that was complete, [Alex] moved to a 4 jaw setup.

Much like the arcade games, the claw is actuated by a central plunger. The plunger drives linkages which move the 4 claw jaws. Everything looks good on paper, but when the CAD drawings meet the real world, things get complicated quickly. The initial design relied on a 3D printed part which connected the plunger to the jaw linkages. Any slop in this part would be magnified through the rest of the mechanical system. 3D printers aren’t perfect, and there was some slop — enough that the parts would pinch and bind up while moving.

[Alex] already has a revised design in mind. This is very much a work in progress. That’s the beauty of well documented projects on Hackaday.io — you get to see what works, as well as all the trials and tribulations it took to get to a final working project. Keep at it [Alex], you’re almost there!

That’s it for this week’s Hacklet, As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

A few years back [James] built an utterly amazing set of Wolverine replica claws. They are held together by a bar that laces between his fingers so that when he’s gripping it you don’t see anything but the claws. Add to that the tail design which makes it look like they’re actually coming out of his skin and he’s made an amazing replica. But they’re also rather utilitarian as you can see in the demo/how-it-was-done video where he spears hay bails as they’re thrown at him from off camera. Machine shop fans are going to love learning how these were made.

More recently he decided to update the project after seeing our own Thor’s Hammer offering. He got down to business by salvaging a huge transformer from an old oil furnace. He has no idea what kind of voltage this thing puts out, but that doesn’t stop him from wiring it up to the pair of claws and letting the sparks fly. He even creates a Jacob’s Ladder effect by placing the claws at a narrow angle to each other.

[Alexey] wrote in to share a mechanical claw (Google Translation) he has been hard at work on for quite some time. While a lot of people will turn to some sort of 3D plastic printer such as the MakerBot if they need plastic parts built, [Alexey] didn’t have access to one. Instead, he carefully crafted the entire mechanism from polycaprolactone, or as it’s more commonly known, Shapelock.

Using a wide range of tools from hair dryers and knives to lighting fixtures, he manually sculpted the claw and its control arm out of plastic, piece by piece. We are particularly impressed by the gearing he was able to cut from the plastic, which can be finicky at times.

As you can see in the video below, The claw mimics each movement he makes with the control arm via a handful of Arduino-driven servos. Everything seems to work quite well, and despite the rough translation by Google, we think this is a great project. If you are looking to do something similar yourself, he has plenty of pictures on his site, which should give you a pretty good idea as to how things were put together.

Grab some stiff paper and get to work building your own paper claw. [Dombeef] posted the instructions to recreate the claw above because he was unsatisfied with his previous design which was flimsy and unable to pick up just about anything. This version is a bit larger and it internalizes all of the parts.

Being paper craft, you don’t need much in the way of materials or tools. A push-pin makes holes for the paperclip and wire which serve as the pivot points. Glue and some tape hold the rest of assembly together. You can see a video of the final product after the break. A shaft at the center closes the claw when pulled, and opens it when pushed to opposite way. This makes it perfect for that home-made crane game (or was that a claw game?)… as long as you’re not trying to pick up anything too heavy.

[Oleg] worked out a way to use his USB mouse to control this manipulator arm. Using a Lynxmotion AL5D (we’ve seen the AL5A previously) he drives the six servos with an Arduino servo shield. A USB host shield handles the HID end for connecting the mouse. The video after the break says it all, [Oleg] has no problem picking up that figurine quickly and accurately. Sliding the mouse controls horizontal movement in all directions. The scroll wheel moves the claw up and down. And holding the left or right buttons what using the control wheel closes or rotates the claw. All we can say is: Bigger, BIGGER!

[David Hyman] built this device to control a LEGO claw. One one end of things is the part you wear, that measures movement of two fingers and your thumb. On the other end of things is a LEGO claw with three opposing digits. You move, it moves. The claw uses light sensors and a gradient strip for position feedback. There is also an up-down wrist action that uses a touch sensor as the input. This is impressive enough to give the sniper rifle a run for its money.